Fuel burning apparatus



Aug. l6 1949.

6 Sheets-Sheet 1 Original Filed March 7, 1941 I), J W w.

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' FUEL BURNING APPARATUS Original Filed March 7, 1941 6 Sheds-Sheet 2 7/l 2 INVENTORS f Howard .1 Kerr, fame; F/efcfier Aug.16, 1949. H. J. KERREI'AL 2,479,240

FUEL BURNING APPARATUS Original Filed March 7, 1941 6 Sheets-SheetfiFig. 7 I Fig.8

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Air Heaier v Water Cooler J x fiy-Pas: lzlx/e Coolin Ca '15 5 I g 5 L ag E HM O r" INVENTORS 'BY George/4 W ls/[muted 1460/3274 m Aug. 16,1949. H. J. KERR ErAL,

FUEL BURNING APPARATUS 6 Sheets-Sheet 5 Original Filed March 7, 1941 |lllillllrl ttorney 1949- H. J. KERR ETAL 2,479,240

FUEL BURNING APPARATUS Original Filed March 7, 1941 e Sheeis- Sheet 6Fig. 14

INVENIORS Howard .1 Keri; James F/e lc/re BY Georqe A Wfl: I ZamberfKn/lstra i o rn ey atented Aug. 16, 1949 UNITED STATES PATENT OFFICEFUEL BURNING APPARATUS Original application March 7, 1941, Serial No.382,264. Divided and this application July 20, 1944, Serial No. 545,776.In Canada February 13 Claims.

The present invention relates in general to apparatus for burningash-containing solid fuels, and more specifically, for burningbituminous and semi-bituminous coals in a'relatively coarsely pulverizedor crushed condition in a furnace of the cyclone type.

The general object of our invention is the provision of an improvedapparatus for supplying fuel of the character described and combustionair to a furnace, and more particularly to a vertically arranged furnaceof the cyclone type in which the fuel is burned at very high rates ofheat release and with a discharge of the gaseous products of combustionfrom the bottom of the furnace and a recovery of substantially all ofthe recoverable ash content of the fuel in a molten condition,

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which are illustrated and described several embodiments of theinvention.

Of the drawings:

Fig. 1 is an elevation of a portion of a test cyclone furnaceinstallation constructed and operable in accordance with this invention;Fig. 2 is a horizontal section taken on the line 22 of Fig. 1; Fig. 3 isan enlarged vertical section taken on the line 33 of Fig. 2 showing thefurnace fuel and air ports; Fig, 4 is a sectional elevation taken on theline 4-4 of Fig. 2; Fig. 5

is an enlarged view of a portion of the furnace wall construction shownin Fig. 4; Fig. 6 is a flow diagram of the steam generating system ofthe installation shown in Figs. 1-5; Fig. 7 is an elevation of amodified fuel feeding arrangement; Fig. 8 is a plan view of the fueldistributor of Fig. 7; Fig. 9 is a vertical section taken on the line 99of Fig. 8; Fig. 10 is an elevation partly in section of a modified formof fuel and air supply provisions; Fig. 11 is an end view partly insection of the construction shown in Fig. 10 looking toward the furnacein Fig. 1 from the right; Figs. 12 and 13 are horizontal sections takenon the lines l2l2 and l3l3 of Fig. 10; Fig. 14 is an elevation partly insection similar to Fig. 11 of another form of fuel and air supplyprovisions; Fig. 15 is a side View, partly in section, of the apparatusshown in Fig. 14; Fig. 16 is an enlarged horizontal secand 6-10% througha ZOO-mesh. screen.

Fig. 17 is a horizontal section taken on the line While various kinds ofliquid, gaseous and solid fuels can be burned in the apparatusillustrated, the apparatus hereinafter described is especially designedand particularly adapted for supplying and burning bituminous andsemi-bituminous coals having an ash fusion temperature below 2800 F. andreduced by crushing or pulverization to an aggregate or mixture ofparticle sizes not over Solid fuel of this general character has beenreferred to as granular or granulated fuel. The fines in the mixturepassing through a 200 mesh screen may be between 3% and 20%, dependingupon the volatile con-' tent of the coal. The minimum volatile contentof the coal may vary considerably, ranging, for example, from 20% for acoal having an ash fusion temperature of 2350" F. to 40% for a coal withan ash fusion temperature of 2700 F. A certain percentage of fines inthe mixture is desirable to aid ignition and promote combustion of theentering fuel, but an excessive amount is undesirable as the amount ofash leaving the furnace as fly ash is proportional. The larger the sizeof the coal particles, the less the amount of fly ash, but the higherthe percentage of coarse particles, the higher the air velocity requiredto keep the particles in motion in the furnace until they are depositedon the slagcovered furnace walls. A consideration of all of the factorsinvolved makes a relatively coarse fuel mixture most desirable. Forexample, a de-y' sirable mixture for bituminous coals having about 11%moisture, 16% ash, 39% volatiles, and a heat value of 10,300 B. t. u.per pound as fired, would be 98-100% through a 4-mesh screen, 40-50%through 30 mesh, 10-18% through IOU-mesh, Coal of the characterdescribed is supplied at a regulable rate from a feeder (not shown)connecting a bin or crusher to a supply pipe 10, the lower end of whichopens into one side of a primary air passage where the entering fuelparticles are swept up by a high velocity stream of preheated air anddelivered to the furnace.

The cyclone furnace consists of an elongated substantially cylindricalcasing i2 arranged with its axis vertical. The casing enclosesrefractory faced fluid cooled Walls defining a vertically elongated mainor primary furnace chamber l5 of approximately circular horizontalcross-section.

The furnace walls include a, circumferential wall l6 defined by a watertube coil H. A coil I8 downwardly through this chamber.

defines the circumferential wall of a subjacent secondary furnacechamber IS. The inner half of the tube portions in the boundary walls ofthe two furnace chambers have metallic studs 20 welded thereon, as shownin Fig. 5, and covered by a layer of suitable high temperaturerefractory 2|, such as plastic chrome ore. A layer of heat insulation 22is placed between each tube coil and the casing [2.

The inner exposed surface of the circumferential wall of the mainfurnace chamber is made to conform as much as possible to a uniformcircular cross-section throughout its height to avoid interference withthe desired helical flow path of the fuel and air and products ofcombustion The main deviation from the desirable uniform circularcross-section is due to the necessary openings for the entry of fuel andair to this chamber and the construction of the circumferential wallportions adjacent the points of fuel and air entry so as to insuremovement of the entering fuel and air in the desired flow path, minimizeinterference with the streams already in the furnace, and to avoidsolidified slag and coke formations on the furnace chamber walls,particularly around the points of fuel and air entry. As illustrated inFigs. 1, 3 and 4, all of the fuel and air is preferably introduced intothe furnace chamber through a plurality of vertically elongated ports invertical alignment and extending over a major portion of the furnacechamber height. The inlet ports are part of a vertically elongated slot23 arranged tangentially to the outer end of a section Hi of thecircumferential wall shaped in the form of an involute curve andextending about one-half the circumference of the furnace chamber. Theslot is defined by connecting vertically adjacent portions of the tubecoil into two radially spaced overlapping groups of 180 bends 25 and 26,the bends 25 bein at the outer end of the involute curved wall sectionI6. The upper end of the slot 23 terminatesslightly below the upper endof the furnace chamber.

The top of the furnace chamber I is closed by a roof 30 formed by a flatstudded tube coil 3| covered on its lower side by refractory material 2I. A central opening in the roof 30 is closed by an access door 32having an inspection opening 31. her I5 is fluid cooled by a coiled tube33 defining a fiat annular outer bottom section 34 and an upwardlyconverging inner throat section 35, the upper and lower sides of theflat tube portions and the outer and inner side of the throat tubeportions being studded and covered with plastic refractory as heretoforedescribed. An annular The bottom of the main furnace chama pocket 28open at its upper side only is thus formed around the downwardly flaringgas outlet 29 defined by the throat 3-5. The coil 33 is seriallyconnected to the tube coil l1 and through a bare tube portion 36 to anintermediate cooling coil 38 arranged in a water tank 39.

An intermediate pair of adjacent tube portion in the throat are formedwith a pair of angularly spaced 180 bends 40 to define therebetween aslag discharge opening 4| slightly 'above the floor level of the pocketand at the side of the throat remote from the secondary furnace gasoutlet. The slag outlet is angularly spaced from the fuel and air inletslot 23, and, as shown in Fig. 2, is preferably located approximately 90rearwardly of the slot 23 relative to the direction a of rotation of thestreams in the main furnace chamber. With this arrangement any slag in afluid condition on the furnace chamber floor will flow towards the slagdischarge opening and drop therethrough into the secondary furnace chamvber IS.

The secondary furnace chamber l9 opens through a gas outlet opening 43to a tunnel 44 in the water tank 39. The chamber l9 has its bottom 45fluid cooled by a flat coil 46 connected to the bottom of the coil 18. Afeed water pump or other means for establishing a circulation isconnected to the coil 46. The coil 46 is studded and covered with alayer of refractory insulation 41 sloping downwardly toward the gasoutlet 43. A slag discharge opening 50 is formed at'the bottom of thechamber [9 below the level of the gas outlet 43. The portions of thetube coil l8 extending across the gas outlet are arranged to form a slagscreen 5|. The heating gases flowing through the tunnel 44 aredischarged through a stack connection 53. A slag outlet is located inthe bottom of the stack connection for the removal of any slag sweptinto the tunnel 44 from the chamber IS. The water circulating system ofthe experimental unit is diagrammatically shown in Fig. 6.

The fuel and air supply provisions comprise a combination hot gas mixingand water heated air heater 6!] having means for discharging two streamsof hot air, heated to different temperatures if desired, through aprimary air duct BI and a secondary air duct 62. The ducts 6| and 62 areconnected to compartments 63 and 64 respectively, of an air casing 65mounted on the cyclone furnace. The casing 65 has a laterally extendingnozzle section 66, the discharge end of which terminates in the furnaceslot 23. The nozzle section 66 is of relatively narrow width throughoutits length, corresponding to the width of the slot 23 and is dividedinto three similar vertically elongated horizontally directed ports 68,69 and 10 by horizontal diaphragms 61. The remaining portion of thecasing is constructed so that the compartment 63 opens only into theport 68 and the compartment 64 only into the ports 69 and 10. Each ofthe nozzle ports is provided with an adjustable damper, the damper II inthe port 68 having a curved outer end and being variable from a wideopen position to a half closed position, as shown in Fig. 3, by threadedrods 15 passing through nuts 16 welded on the side of the casing, theinner end of each rod having a loose connection with the correspondingdamper to permit the rod to turn. A stationary curved baffle l4cooperates with the curved outer end of the damper II to preventby-passing of the port area controlled by the damper. The dampers I2 and13 in the secondary air ports 69 and 10 respectively are fiat and hingedat their outer ends so that they are variable over the full width of thecorresponding port without changing the position of the air streamsrelative to the involute curved circumferential wall section. Thedampers I2 and 13 are adjusted by a single control rod 15, while thedamper II is controlled by two pairs of vertically spaced control rodsto permit a uniform lateral adjustment of this damper and thus pipe H1is connected to the top port 68 through a rectangular opening in theupper part of one side thereof to supply a controlled amount of fuel tothe high velocity stream of preheated air passing through the port.Orifice plates 11 are positioned in the air supply ducts 6| and '62 tofacilitate the measurement and control of the air suplies.

p The cyclone furnace construction described permits the efficientburning of fuel of the character described at very high rates of heatrelease with only a small percentage of excess air over a wide range ofratings and separation and removal of a high percentage of the ashcontent of the fuel in a molten condition before the gaseous products ofcombustion leave the furnace. In operation the furnace is initiallypreheated by an oil or gas burner temporarily inserted therein. The fueland air supplies are then controlled toprovide a mixture of the fuelparticles and primary air which is discharged at a high velocity throughthe port 68, and a supply of high velocity secondary air through one orboth of the secondary air ports 69 and I0. The total air supply isdirectly proportional to the amount of fuel supplied to the furnace, thefuel-air ratio maintained being such that the total air supply is notmore than about and preferably less than 15%, in excess of thetheoretical combustion air requirements. The air-fuel ratio may bevaried to some extent as a lower excess air ratio is usually desirableat the higher fuel rates to increase the adiabatic furnace temperatureand facilitate sla tapping. About one-third of the air supply isdelivered to the primary air port. Due to the admission of the fuel fromthe pipe l0 into the upper part of the port 68 and the high velocity ofthe air passing through that port, the discharge therefrom into thefurnace will usually consist of an intimate mixture of fuel and air fromthe upper part of the port and substantially clean combustion air fromthe lower part.

The entering vertically elongated stream of primary air and fuel isdirected horizontally along the involute curved section of thecircumferential wall of the furnace chamber and as it moves therealongis exposed to the high temperature conditions present in the furnacechamber. The fines in the fuel mixture are ignited almost immediately onentrance and the combustion of the fines aids the ignition andcombustion of the larger fuel particles as the stream whirls around theupper end of the furnace chamber in a film along the circumferentialwall. Due to the location of the discharge throat, gravity, and thecontinuous tangential entry of primary air and fuel, the stream ofburning fuel particles, air and products of combustion will follow ahelical path downwardly along the circumferential wall. The rapidcombustion of the fuel particles results in an early release of the ashcontent thereof, and due to the centrifugal effect thereon, the ashreleased is deposited on the furnace walls, and particularly thecircumferential wall, resulting in the formation of a thin layer or filmof molten ash or slag, which adheres to the refractory surface of thewalls and quickly provides a sticky surface to which fuel particles,particularly the larger fuel particles, in the whirling fuel and airstream, will adhere and be completely burned thereon. The rate ofcombustion of the fuel particles held on the furnace walls issubstantially increased by the scrubbing action of the contacting air.The use of preheated primary air is particularly desirable to facilitatethe ignition of the entering fuel. With the cyclone furnace constructedand arranged as described it is deemed essential for efficient operationthat the primary air-fuel stream should always enter the furnace chamberat a point above the level of the secondary air admission ports. 1

The secondary air enters the furnace through the ports 68 and I0 in thesame angular direction and at a high velocity of the same order as thatof the whirling stream of primary air and fuel. The secondary air streamintimately mixes with the stream of burning fuel, air, and products ofcombustion and passes downwardly therewith in the helical path of flow.Combustion of the remaining fuel particles in suspension approachescompletion as the whirling stream reaches the bottom of the furnacechamber l5. At this point and due to the location and configuration ofthe throat 35, the whirling stream is forced to move inwardly andupwardly to reach the gas outlet through the throat. This relativelyabrupt axial reversal in direction of movement of the stream results inash or slag particles in suspension being thrown out of the whirlingstream and deposited on the furnace bottom around the throat. Anyincompletely burned fuel particles will separate out of the gas streamin this flow reversin zone due to the gravity and inertia effectsthereon and will remain in the annular pocket 28, either partly embeddedin the slag surface therein or moved around in the pocket by thewhirling gases therein, until all of the combustible content is consumedand the ash content released. The location of the slag outlet 4| in thethroat above the bottom of the pocket insures a slag layer therein underall operating conditions. The slag coating on the furnace walls rapidlyreaches an equilibrium thickness, which is dependent upon the relativevalues of the furnace wall temperature, the ash fusion temperature, themean furnace chamber temperature, and the velocity of the contacting gasstream. The deposition of additional slag results in a flow of slag downthe furnace walls to the furnace chamber floor. The molten slagaccumulating on the furnace floor overflows through the slag dischargeopening 4| into the secondary furnace chamber l9,

' where it flows down to the floor thereof to the slag outlet 50. Thefurnace gases flow downwardly through the gas outlet 29 into thesecondary furnace chamber, turn therein and flow through the outlet 43and tunnel 44 to the stack connection 53.

The relative arrangement of the primary airfuel and secondary air portsdescribed is particu-' larly advantageous in minimizing slag formations0n the circumferential wall at points where they would interfere withthe entry of either the fuel or air. Slagdepositing in any nozzle portwould cause an increase in the flow resistance therein andcorrespondingly reduce the fuel or air supply therethrough. Suchaccumulations would also tend to disrupt the air and fuel flow path inthe furnace and to destroy the desired whirling of a the stream alongthe furnace chamber circumferential wall. With the air and fuel streamentering the furnace chamber tangentially to an involute curved wallsection extending a substantial distance, the entering streams have anopportunity to gradually merge with the whirling furnace gases beforeintimate contact with the descending slag. Only the secondary air portsare in a position wherein there is any tendency for slag formations toform adjacent the point of entry. Any such formations can be quicklyremoved without shutting down the furnace by momentarily reducing orshutting oil. the secondary air supply through the nozzle port affected,and supplying all the secondary air through the other nozzle port. Withthis operation any slag accumulations at or adjacent the level of theclosed port will be quickly melted and thus eliminated. The relativeposition of the refractory faced roof of the furnace chamber I and thefuel inlet port insures a high furnace temperature in the fuel entrancezone of the furnace chamber and thereby the absence of coke formationsin this area, and particularly at the trailing edge of the fuel port.

By way of example, and not of limitation, one test run of theexperimental installation illustrated in Figs. l-6, gave the followingvalues which indicate representative conditions to be maintained inaccordance with the present in vention. The fuel burned was Ohio No. 8coal reduced to the following sizing:

85.9% through No. 4 mesh 53.4 through No. 10 mesh 24.1% through No. mesh16.8% through No. mesh 10.8% through No. 100 mesh 6.7 through No. 200mesh A proximate analysis of the coal showed 3.7 Heat valuedry 13,020 B.t. u./lb.

The ash as analyzed showed an initial deformation temperature of 2120F., a softening temperature of 2210 F., and a fluid temperature of 2430F. The coal was fired at a. rate of 2280 lbs. per hr. with an excess airof 19.5%. The total air supplied was'25,700 lbs. per hr., of which26.85% was supplied as primary air, and 73.15% as secondary air throughboth of the secondary air ports. The air velocity through the primaryair port was 21,000 ft. per minute and through the secondary air ports22,000 ft. per minute. The average velocity of the gases passing outthrough the throat 35 was calculated as 30,350 ft. per minute. The airwas supplied at a. temperature of 390 F., and the furnace temperaturewas approximately 3200 F. The heat release was 1,087,000 B. t. u. percu. ft. of furnace volume. About 93% of the recoverable ash content ofthe fuel was removed as molten slag and found to be practically free ofcombustible matter.

Good operating conditions may be defined as those resulting in 16% to17% CO with no coke or sla formations around the furnace chamber inlets,a continuous flow of slag through the slag opening 4| and steady flameconditions in the furnace chamber.

fuel entry as the rate of fuel firing decreases. For the best resultswith such operation, substantially. all of the secondary air suppliedshould be admitted below the level of the fuel entry point.

In Figs. 7-9 a modified arrangement of fuel supply means is illustratedin which fuel can be supplied to any one or combination'of ports. In themodified construction a three-way distributor 80 in the fuel supply pipeI0 permits the fuel to be divided between three separate pipes BI, 82,and 83 leading into the sides of the nozzle ports 68, 69, and I0respectively. The coal supply to the individual ducts is separatelycontrollable by individual hinged valves 85, as illustrated in Fig. 9,whereby coal may befedto any one of the three ports alone or incombination with one or both of the remaining ports. The effective widthof each port is controllable by a. hinged fiat damper 86 similar to thedampers 12, I3 shown in Figs. 2 and 3, and capable of independentadjustment to close off the air supply through any port. Good operationhas been attained at the higher fuel ratings with fuel and air passedthrough all of the ports. or only the top port with air alone throughthe middle and bottom ports; at intermediate ratings with fuel and airdischarged through the top and middle ports 68 and '69, or the middleport alone, and secondary air through the bottom port I0, and at lowratings with all of the fuel and air through the bottom port I0 and thetop and middle ports closed off. It is highly desirable in any casewhere fuel is supplied through only the middle or bottom ports that noair be supplied through any higher port. In one test run in which all ofthe air and coal of the character described were passed throug thebottom port and the top and middle ports completely blocked off, thecoal was fed at a rate of 480 lbs. per hr. with 20.69% excess air. Thetotal supply of air at 5550 lbs. per hour was supplied to the bottomport at a velocity 'therethrough of 10,000 ft. per minute, and atemperature of 376 F. The furnace temperature by optical pyrometer was2855 F., and the heat release rate 226,800 B. t. u. per cu. ft. perfurnace volume. The slag flowed freely to the secondary furnace chamberand operating conditions were good. The fly ash amounted to 1.2 of thefuel with a carbon content of 0.75%

In the modifications illustrated in Figs. 10-17,

the point of admission of the fuel and combustion air supplied can bevaried relative to the furnace chamber height as desired, thuspermitting regulation of the length of travel of the entering fuel andair in the furnace chamber. in accordance with changes in fuel rating,or any other varying operating condition.

In the modification illustrated in Figs. 10-13,

the points of entry of the fuel and air into the With the constructionillustrated in Figs. 1-6

operating as described, the length of the helical path of travel of thefuel and air downwardly through the furnace chamber will besubstantially the same at all ratings and be approximately the maximumlength attainable in such a furnace. It has been found that improvedoperating conditions over a wide range of ratings can be obtained if thepoint of fuel entry, and thereby the length of travel in the furnacechamber before reaching the gas outlet, is varied with the rating, andparticularly by lowering the point of furnace chamber are simultaneouslycontrolled with the same relative positions of the entering fuel and airstreams maintained throughout the range of adjustment. For this purposethe air duct nozzle section 66 has a vertically inclined open endedstationary tube I20 mounted thereon and within which is concentricallypositioned a stationary fuel pipe IZI connected at its upper end to thefuel supply pipe I0. The pipes I20, I2I have an annular spacetherebetween throughout their length and terminate at a flanged openingI22 in the top of the duct section 66. The annular space described isfor the reception of a telescoping continuation of the fuel pipe l2lconsisting of an open ended pipe I23 surrounding the pipe I2I andprovided with a pair of lateral in the slots I20 and are held in anydesired vertical position relative to the tube I20 by a combined sleeveand set screw I23. The direction of air'travel in the duct section isindicated by the arrows in Figs. l0'and 13, and the pipe I23 is soinclined that its lower end leads its upper end relative to thedirection of air travel.

The lower end of the pipe I23 has a reduced extension I 23 for receivingvarious types of fuel tips. The tip I30 illustrated has been foundparticularly effective in operation in securing a distribution of thedescending fuel particles over a substantial part of the height of theduct section 65 and consists of a sleeve I3I fitting over the pipeextension I29 and a downwardly tapering tongue I32 formed by cuttingaway all but a narrow sector of the sleeve wall at the outer sidethereof. 1 I p With the construction described, the stream of fuelparticles flow down. through the pipes I0 and I2I into the pipe I23. Theamount of fuel supplied is normally not sufllcient to fill the entirecross-section of these pipes and thefuel stream tends to concentratealong the side of the pipe I23 facing the incoming high velocity airstream. The descending fuel stream tends to continue down along theconcave face of the tongue I32 subject to the action of the air streamsweeping around the sides of and below the tongue. The pipe I23 andattached wings I24 act as a damper for the air duct section 66,concentrating the air fiow therethrough to the portion of the duct belowthe wing level. The pipe I23 is shown in its lowermost position, whichwould normally be used for the lowest rating for which the furnace isdesigned. As the pipe I23is raised, such as for of 2200" F. The coal wasfired at the rate of.

2448 lbs./hr. using 6.3% excess air. The air velocity through the burnerwas 18,300 ft./min., and through the throat 22,100 ft./min., the airtemperature at the furnace inlet being 442 F.

The ash recovered through the slag holes in the secondary furnacechamber and tunnel amounted to 95.3% of the recoverable ash in the coal.The flue gas analyses averaged 17.31% 00:, 1.28% Oz, and 0% C0.Operating conditions during and at the end of the test run were good,and the only accumulation in the furnace chamber was a thin layer ofslag on the furnace walls.

In the modified burner assembly illustrated in Figs. 14-17, the point ofentry of the fuel stream into the duct section 00, and consequently thefurnace chamber, and theeffective height of the air stream in the ductare separately variable. In this arrangement the fuel pipe l0 has avertical extension I40 positioned in a rectangular casing I, mountedalongside and extending above the air duct section 00. A movable burnerpipe I42 is also positioned in the lower part of the casing I intelescoping relation with the lower end of, the pipe I40. The lower endof the pipe I42 extends downwardly and laterally, as indicated at I43,and carries a vertical guide plate I 44 around its discharge end. Theguide plate I44 is positioned in vertical slots I45 in .the side of theduct 56. The fuel pipe I42 can be raised and lowered relative to theduct 56 by the hand wheel I41 operating through a pinion gear I48 and arack I49 on the side of the pipe. With this arrangement the position ofthe fuel'pipe can be vertically'adiusted inthe casing I to vary theposition ,of its discharge end I43 relative to the duct section 00,

through which a stream of high velocity air is passed in the directionindicated by the arrow in Fig. 17. The effective height, of the airstream in the duct section is controlled by a higher fuel ratings, agreaterpercentage of the with a cyclone furnace construction andarranged as illustrated in Figs. 1-5. 'Inone 24-hour test run of acyclone furnace with such a fuel burner assembly, the fuel burned wasKincaid coal having the following proximate analysis:

. Percent Volatile matter 39.7 Fixed carbon 43.2 Ash 17.1 Moisture (asfired) 11.4

Heat content (as fired) 10,300 B. t. u. per pound The fuel was reducedto the following sizing:

100% through No. i-mesh screen 81.2% through No. 10-mesh screen 37.2%through No. 30-mesh screen 21.2% through No. 50-mesh screen 10.9%through No. 100-mesh screen 5.7% through No. 200-mesh screen The ash asanalyzed showed an initial deformation temperatureof 1990 F., asoftening temperature of 2060" F., and a fluid temperature verticaldamper I50 mountedin guide slots in the sides of the duct section."immediately in advance of the point of fuel entry. The posi-- tion ofthe damperis vertically adjusted by means of a rod I5I on its upper end.The damper and rod are held in any desired position by a sleeve I53mounted on the rod at the upper end of a vertical extension I54 of thedamped guide slots, and a set screw I55.

With this arrangement the discharge end of,

the fuel pipe I43 is adjusted to the proper position for thecorresponding fuel rating, and the damper I50 is correspondinglyadjusted so that it is normally in a position with its lower endterminating slightly above the upper end of the fuel outlet, asindicated in Fig. '14. The stream of high velocity air sweeping throughthe duct 66 below the damper I50 picks up the fuel particles dischargedthrough the lower end of'the fuel pipe and discharges them intothe-furnace chamber. As in the burner assembly illustrated in Figs.10-13, the upper portion of the air stream will act as primary air,while the lower portion will be in eifect secondary air.

This application is a division of our prior application, Serial No.382,264, filed March U. S. Patent No. 2,357,303.

We claim: 1. Apparatus for burning a reduced solid in comprising afurnace structure having a vertically elongated fuel inlet port, avertically elongated air duct connected to said fuel inlet port,fueldischarge means arranged to discharge a reduced solid fuel into saidair duct in contact 7, 1941, now

' a reduced solid fuel into said air duct in contact with the air streamtherein comprising an opening in one side of said air duct. a verticallyslidable plate in said opening having an adjustable fuel pipe discharing therethrough, means for varying the position of said plate and thedischarge end of said fuel pipe relative to said air duct, a verticallyslidable damper in said air duct adjacent the point of fuel entrythereto, and means for adjusting said damper to regulate the height ofsaid air stream adjacent the point of fuel entry.

3. Apparatus for burning a solid fuel comprising a furnace structurehaving a fuel inlet port, an air duct connected to said fuel inlet port,fuel discharge means arranged to discharge a solid fuel in a reducedcondition into said air duct in contact with the air stream therein andadjacent said inlet port, and means for changing the eifective fuel andair discharge area of said inlet port including means for varying theposition of the discharge end of said fuel discharge means in said airduct and simultaneously regulating the effective flow area of said airstream adjacent the point of fuel entry to said air duct.

4. Apparatus for burning a reduced solid fuel comprising a furnacestructure having a vertically elongated fuel inlet port, a verticallyelongated air duct connected to said fuel inlet port. fuel dischargemeans arranged to discharge a reduced solid fuel into said air duct incontact with the air stream therein comprising a vertically movable fuelpipe in said air duct having a tongue extension at its lower end ofsmaller width than said air duct, and means for varying the position ofsaid tongue extension in said air duct.

5. Apparatus for burning a reduced solid fuel comprising a furnacestructure having a vertically elongated fuel inlet port, a verticallyelongated air duct connected to said fuel inlet port, fuel dischargemeans arranged to discharge a reduced solid fuel into said air duct incontact with the air stream therein comprising a vertically movable fuelpipe extending the full width of said l2thepositionofsaidguidewingstoregulatethe height of said air streamadjacent the point of fuel entryto said air duct.

'1. Apparatus for burning solid fuel comprisinga furnace structurehaving a vertically elongated fuel inlet port, a vertically elongatedair duct connected to said fuel inlet port, fuel discharge meansarranged to discharge a solid fuel in a reduced condition into said airduct in contact with the air stream therein comprising an opening in oneside of said air duct, a vertically slidable plate in said openinghaving an adjustable fuel pipe discharging therethrough, and means forvarying the position of said plate and the discharge end of said fuelpipe relative to said air duct.

8. Apparatus for burning solid fuel comprising a furnace structurehaving a fuel inlet put, an air duct'connected to said fuel inlet Port.fuel discharge means arranged to discharge a solid fuel in a reducedcondition into said air duct in contact with the air stream thereincomprising an opening in one side of said air duct,-a slidable plate insaid opening having an adjustable fuel pipe discharging therethrough,means for varying the position of said plate and the discharge end ofsaid fuel pipe relative to said air duct, a slidable damper in' said airduct adjacent the point of fuel entr thereto, and means for adiustinsaid damper to regulate the effective flow area of said air streamadjacent the point of fuel entry.

'9. Apparatus for burning a reduced solid fuel comprising a furnacestructure having a transversely elongated fuel and air inlet port, acorrespondingly elongated air duct having its discharge end registeringwith said fuel inlet port,

- fuel discharge means arranged to discharge a rearea thereof, and meansfor regulating the eii'ec- V tive cross-sectional flow area of said airstream air duct, and a downwardly p red tongue of said fuel pipearranged to close the corresponding portion of said air duct, and meansfor varying the position of the discharge end of said fuel pipe in saidair duct and simultaneously varying djacent to the location of fuelentry into said air duct.

10. Apparatus for burning a reduced solid fuel comprising means forminga furnace chamber of substantially circular cross-sectional area, an airduct having a tangential connection into said furnace chamber adjacentone end thereof, said air duct having a cross-sectional shape elongatedaxially of said furnace chamber, fuel discharge conduit means opening tosaid air duct closely adjacent to said furnace chamber and arranged todischarge a reduced solid fuel into said air duct in contact with theair stream therein, means for varying the effective position of thedischarge end of said fuel discharge conduit means relative to thecross-sectional area of said air duct in the direction ofcross-sectional elongation thereof, and means for regulating theeifective cross-sectional flow area of said air stream adjacent to thelocation of fuel entry into said air duct.

11. Apparatus for burning a reduced solid fuel comprising means forminga vertically arranged said air duct, fuel discharge conduit meansopening to said air duct closely adjacent to said furnace chamber andarranged to gravitationally discharge a reduced solid fuel into said airduct in position to be swept up by the air stream therein, and means forvarying the effective position of the discharge end of said fueldischarge conduit means relative to the vertical dimension of said airduct, whereby to vary the length of fuel travel axially of said furnacechamber while maintaining a uniform direction of fuel entry into saidfurnace chamber.

12. Apparatus for burning a reduced solid fuel comprising means forminga furnace chamber of substantially circular cross-sectional area about asubstantially vertical axis and having a vertically elongated fuel andair inlet port opening tangentially into said chamber adjacent the upperend thereof, a vertically elongated air duct having its discharge endregistering with said inlet port and directed tangentially of saidchamber, fuel discharge means having an opening to said air duct closelyadjacent to said furnace chamber, said opening being-of relatively smallarea in comparison with the flow area of said duct and of less heightthan said duct and arranged to discharge a reduced solid fuel into saida substantially vertical axis and having a ver-' tically elongated fueland air inlet port opening tangentially into said chamber adjacent the 1upper end thereof, a vertically elongated air duct having its dischargeend registering with said inlet port and directed tangentially of saidchamber, fuel discharge means having an opening to 45 said air ductclosely adjacent to said furnace chamber, said opening being ofrelatively small area in comparison with the flow area of said duct andof less height than said duct and arranged to gravitationally dischargea reduced solid fuel into said air duct in position to be swept up bythe air stream therein at a location intermediate the height of saidduct and adjacent the radially outer tangential boundary thereof, avertically slidable damper in said air duct closely adjacent to thepoint of fuel entry thereto, at the upstream side of said point, andmeans for adjusting said damper to regulate the eflective height of saidair stream adjacent to said point of {uel entry relative to the lowerend of said por HOWARD J. KERR. JAMES FLETCHER. GEORGE A. WATTS. LAMBERTKOOISTRA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 739,957 Walker Sept. 29, 903824,728 Larsen July 3, 1906 930,127 Bassler Aug. 3, 1909 987,834 SeldenMar. 28, 1911 1,306,235 Schutz June 10, 1919 1,421,898 Bergman July 4,1922 1,454,979 Muhlfeld, et a1 May 15, 1928 1,591,679 Hawley July 6,1926 1,618,808 Burg Feb, 22, 1927 1,657,698 Schutz Jan. 31, 19281,838,667 Frisch, et a1 Dec. 29, 1931 2,242,787 Lieberherr May 20, 19412,357,303 Kerr, et al. Sept. 5, 1944 FOREIGN PATENTS Number Country Date297,835 France Sept. 25, 1928

